Isomerization of normal butane



Oct. 13, 1959 v. HAENsEL IsoMERIzATIoN oF NORMAL BUTANE Filed Jan. ll,1956 l d y m f y IV i! l MH M A N. 0./ AE R SBQ Nm www wm um m Ar dmmWAww\ n f f v.,. L? mw Q Smal u n d. I E ,.r m 1| v m Al A n W H mmQMS k n l l M. QEQ QQ um m f v t Q uw Q Q s l. lv Q S T 1| S t lv MV Ivvm mmmu 1 #if i I l 4, 2,908,735 Patented Oct. 13, 1959 ISOMERIZATION OFNORMAL BUTANE Vladimir Haensel, Hinsdale, Ill., assignor, by mesneassignments, to Universal Oil Products Company, Des Plaines, lll., acorporation of Delaware Application January 11, 1956, serial No. 558,502

4 claims. (ci. 26o-683.68)

thereof. My catalytic agent also includes a small amount of a halogensuch as iluorine, chlorine, bromine and/or iodine.

In one embodiment my invention relates to a process for isomerizing anisomerizable organic compound 'which comprises subjecting said compoundto contact at isomerizing conditions with a catalyst comprising alumina,platinum, 'and combined halogen.

In a specific embodiment my invention relates to a process forisomerizing normal butane, which comprises subjecting normal butane tocontact at isomerizing concatalytic composition which is utilized toeffect the desired isomerization.

In recent years with the advance of the automotive industry and theaviation industry, fuels of relatively high antiknock rating have beenfound necessary. Many methods have been provided for producing thedesired high antiknock fuels. These methods include such processes asalkylation, catalytic reforming, catalytic cracking, and hightemperature thermal cracking and thermal reforming operations. Otherprocesses which may be considered in a sense auxiliary were developedas, for example, isomerization which was employed to produceisoparatiins which subsequently were reacted with oleiins to form a highoctane number motor fuel fraction, commonly termed alkylate. In additionto the production of one of the reactants for alkylation, isomerizationwas also utilized to increase the antiknock quality of saturatedhydrocarbons such as paraflins and naphthenes found in selectedfractions of gasolines and naphthas. This invention is specificallyconcerned with the isomerizing of normal butane to provide isobutane.The isobutane product of this invention may be utilized for variouspurposes, including alkyla-- tion reactions. The preferred alkylationreaction comprises combining isobutane with ethylene, propylene,butylenes, etc. to produce a mixture ofrhigher isoparatlinichydrocarbons boiling within the gasoline range and having a high octanenumber.

In most isomerization processes, catalytic agents are employed to effectthe desired molecular rearrangement. Ordinarily, these catalytic agentsconsist of metal halides such as aluminum chloride, aluminum bromide,etc., which are activated by the Iaddition of the corresponding hydrogenhalide. 'Ihese catalytic materials are very active and eifect very highconversions per pass. However, this high activity is disadvantageous insome respects. One of the greatmt disadvantages is the fact that thesecatalytic :materials not only accelerae the isomerization reaction, but'also induce decomposition reactions. The latter are particularlydetrimental to the economics of the operation in that they cause theloss of an appreciable portion of the charging stock as well asconsiderably increased catalyst consumption by the reaction offragmental material with the catalytic agent to form sludge-like ditionswith a catalyst comprising alumina, platinum, and combined halogen.

In a further embodiment, my invention relatesto a process forisomerizing normal butane which comprises subjecting normal butane at atemperature of from about 400 F. to about 950 F. and a pressure of fromabout 15 to about 1500 lbs..per square inch to the action of a catalystcomprising `a major portion of alumina, from about 0.01% to about 1% byweight of platinum and from about 0.1% to about 10% by weight ofcombined halogen.

In a more specific embodiment, my invention relates to a process forisomerizing normal butane, which comprises subjecting normal butane at atemperature of from about 400 F. to about 950 F. and a pressure of fromabout 15 to about 1500 lbs. per square Iinch to the action of a catalystprepared by forming a mixture of alumina and halogen ions, the halogenions being in an amount of from about 0.1% to about 10% by Weight ofsaid alumina on a dry basis, thereafter compositing platinum with themixture, and subsequently heating the composite.

While the process of my invention is applicable to the isomerization ofisomerizable organic compounds, includ-y ing parains containing 5 to l2or more carbon atoms per molecule, for example normal pentane, normalhexane, etc., cycloparains, aromatics, organic acids, alcohols, ethers,and the like, it is more particularly applicable to the isomerization ofnormal butane.

The charge stock to my process should be a normally gaseous charge stockwhich is predominantly normal butane. It is preferred that normal butanebe present in amounts of at least 75% by Iweight of the charge stock andstill more preferable in amounts of at least 90% by Weight. The bestcharge stock is substantially pure normal butane.

The process of my invention may be carried out by employing a fixed-bedyof catalytic material disposed within the reaction zone, through whichthe hydrocarbons in admixture with hydrogen, if desired, are passed, andthe reaction products then introduced into suitable fractionationequipment wherein `the desired products are materials. I have discovereda catalytic agent which can be effectively employed for theisomerization of normal' separated. Y

Alternatively, the reaction may be conducted by employing a finelydivided catalyst material disposed in a confined reaction zone throughwhich the vaporous charge is passed at a rate suicient to effect theiiuidization of the iinely divided catalyst material so that the chargecontacts the catalyst in a relatively dense bed of rapidly movingparticles and is thereafter separated from entrained catalyst and passedthrough the desired fractionation system as above. This latter method isparticularly adaptable to this operation since the isomerizationreaction is mildly exothermic. The catalyst can be Withdrawn from thereaction zone, cooled, and returned to the zone Vto regulate thereaction temperature at a substantially constant level. i

Still another modification consists of employing a catalytic material inthe form of a relatively compact bed which is passed downwardly from thereaction Vzone and is contacted with a charge in the vapor state eithercon-l` V currently or countercurrently.

The isomerization reaction may be conducted at temperatures within therange of from about 400` to about 950 F. under a pressure ofV from about15 to 1500 lbs. per square inch and a space velocity, measured asvolumes of liquid charge per volume of catalyst per hour, of from about0.1 to about 2O or more.

The catalyst for use in my process comprises a refractory metal oxidecontaining minor amounts of combined halogen and platinum. A preferredtype of catalyst comprises platinum-alumina-combined halogen catalyst ofthe type desscribed in my U.S. Patent No. 2,479,109, issued August 16,1949. These catalysts may contain substantial amounts of platinum, but,for economic as well as 4for product yield and quality reasons, theplatinum content usually will be within the range of from about 0.01% toabout 1% by weight. These catalysts also contain a relatively minoramount of a halogen, especially uorine or chlorine. On a dry aluminabasis, the halogen content usually will be within the range of fromabout 0.1% to about by weight. Since fluorine generally is more activethan chlorine, the amount of lluorine incorporated in the catalystusually will be somewhat less than the amount of chlorine necessary togive a desired activity. The precise manner in which the halogen ispresent in the catalyst is not known, but it is believed to be combinedwith one or more of the constituents. Consequently, it is often referredto as combined halogen.

One method of preparing catalyst useful in my process comprises adding asuitable alkaline reagent such as ammonium hydroxide, or carbonate to asalt of aluminum such as aluminum chloride, aluminum sulphate, aluminumnitrate, etc., in an amount suiiicient to form aluminum hydroxide whichupon drying is converted to alumina. The halogen may be added to theresultant slurry in the form of an acid such as hydrogen fluoride,hydrogen chloride, etc., or as a volatile salt, such as ammonium uoride,ammonium chloride, etc. Platinum, or one of the other metals of theplatinum group, may be added to the alumina by adding hydrogen sulfideto a solution of a platinum compound commingling the resulting solutionwith the halogen-containing alumina, and thereafter heating theresultant composite to a temperature of from about 800 to about 1200 F.

I ordinarily prefer to employ hydrogen in my process in order torestrict the amount of carbonaceous material deposited upon thecatalyst, and to thereby prolong the life of the catalyst. The hydrogen:hydrocarbon ratios that I normally prefer to employ range from about 0.5to about 10.

The following is a brief description of one method of conducting theoperation employing a xed bed of catalytic material.

Referring to the drawing the normal butane feed is introduced to line 1,containing valve 2, and is passed into pump 3, which discharges throughline 4, valve 5, and into reactor 6. The catalyst disposed withinreactor 6 may be of finely divided shape such as granules, spheres, orother shapes formed by extrusion pelleting, etc. The catalytic agent, ashereinbefore stated, is a multiple component material, but in everyinstance must contain the following three components:

(1) Refractory metal oxide (2) Platinum (3) Combined halogen Theoperating conditions maintained in reactor 6 will comprise a temperaturewithin the range of from about 400 F. to about 950 F. a pressure withinthe range of from slightly superatmospheric to about 1500 lbs. persquare inch, and a space velocity within the range of from about 0.1 toabout 20. The particular conditions selected for any operation will bedependent upon the specific catalyst employed, the charging stockutilized and the extent of conversion desired. In the modification shownin the attached drawing, hydrogen is introduced CII . 4 into thereaction zone along with the normal butane. This hydrogen is introducedinto the system as needed through line 12 containing valve 13 and ispassed through line 10 on the suction side of compresser 14 whichdischarges through line 15 containing valve 16 into line 4 through whichit is directed into reactor 6.

Reaction products consisting of isobutane, normal butane, and hydrogenare withdrawn from reactor 6, through line 7, containing valve 8, andare directed into fractionator 9, wherein the hydrogen is separated fromthe higher boiling constitutents and recycled to the reactor throughline 10 as previously described. In many cases it has been found thatfractionator 9 can be dispensed with and a simple separator employedwhen the reactor eluent passing through line 7 is cooled to condense thenormally liquid hydrocarbons. In such a case, the hydrogen separates asa gas from the liquid hydrocarbons and may be recycled as hereinbeforedescribed. The hydrogen-free material is withdrawn from the bottom offractionator 9 through line 17 containing valve 18 and is passed intofractionator 19 wherein the desired product is separated from theunconverted material and the recovered overhead through line 20containing valve 21. The unconverted material is withdrawn through line22 containing valve 23 and is recycled to line 1 from whence it passesinto reactor 6. In order to avoid a build-up of degradation products inthe system, a bleed line has been provided on the bottom withdrawal offractionator 19 from which a minor proportion of the bottoms can bewithdrawn from the system through line 24 containing valve 25 intosuitable fractionation equipment (not shown in the drawing) in which theunconverted charge is separated to be returned to the reactor.

The following examples are given to illustrate my invention but are notintroduced with the purpose of unduly limiting the same.

EXAMPLE I The following results were obtained upon reacting normalbutane in the presence of hydrogen, at a hydrogen to hydrocarbon moleratio of 6 to 1 and an hourly hquid space velocity of 2, using aplatinum-aluminauorine catalyst. The pressure was varied from lbs. persquare inch to 700 lbs. per square inch. The conditions and results aregiven below in Table I.

ethane, and propane. The isomerization reaction is, however, thepredominating reaction at all operating pressures.

The above data in Table I indicates the exceptional activity of thecatalyst in the isomerization of paranic hydrocarbons.

EXAMPLE II Several catalysts were tested to compare the activity of thevarious components for the isomerization of normal butane. The chargestock used was 98.6% by weight pure normal butane, 0.7% isobutane, 0.1%propane, 0.2% ethane and 0.1% methane. The normal butane was reacted inthe presence of hydrogen at a hydrogen to hydrocarbon mol ratio of 1 tol and a liquid hourly space velocity of l0. The catalyst temperature was851 F. and the total pressure 300 lbs. per square inch gauge. Thecatalysts used were alumina with platinum and/or chlorine. The catalystcompositions and results are given below in Table II.

The above data clearly illustrate the unexpectedly high activity of analumina-platinum-halcgen catalyst for isomerization of normal butane.Platinum and alumina has no detectable isomerization activity and analumina-chlorine catalyst has no detectable isomerization activity fornormal butane. Adding the amounts of catalytic components, that is`adding the amounts of catalytic components in columns A and B, it mightbe expected that a catalyst containing 0.375% by Weight of platinum and1.22% (0.06% |1.16%) by weight of chlorine would produce 0.0% by Weightof isobutane. However, 9.5% by Weight is produced. This clearlyillustrates the unexpected high selectivity of the particular catalystfor the process of isomerizing normal butane. EXAMPLE III A straight-nunnaphtha having an initial boiling point of 189 F. and an end point of388 F. was blended with normal butane and the blend contained 15%,normal butane by weight. This blend was reformed in the presence of acatalyst containing alumina, 0.3% by Weight of platinum and 0.5% byWeight of iluorine. The reaction was conducted at 700 lbs. per squareinch pressure, a 3.0 hourly liquid space velocity, 932 F. temperature,and in the presence of hydrogen at a hydrogen to hydrocarbon mol ratioof 7 to 1. At these conditions the hourly liquid space velocity for thenormal butane only was approximately 0.5. Only 2.7% of the normal butanewas isomerized to isobutane at these conditions.

Norman butane of 98.6% purity by weight was then reacted at these sameconditions, except a space velocity of 2.0 was employed. At theseconditions 21% of the normal butane was converted to isobutane.Therefore, even though the space velocity in respect to normal butanewas higher (2.0) than in the runs Where the normal butane was blendedwith the naphtha (0.5) the conversion was much higher, in this case .21%compared to 2.7%. This example establishes that the con- Version ofnormal butane to isobutane in the presence of analumina-platinum-halogen catalyst is unexpectedly high when asubstantially pure normal butane charge stock is used.

I claim as my invention:

1. A process for the production of isobutane from a substantially purenormal butane charge which comprises subjecting said charge at anisomerizing temperature up to about 950 F. and a pressure from about 15to 1500 lbs. per square inch to the action of a catalyst comprising amajor portion of refractory metal oxide, from about 0.01% to about 1% byWeight of platinium and from about 0.1% to about 10% by weight ofcombined halogen.

2. A process for the production of isobutane from a substantially purenormal butane charge which comprises subjecting said charge at anisomerizing temperature up |to about 950 F. and a pressure from about 15to 1500 lbs. per square inch to the action of a catalyst comprising amajor proportion of alumina, from about 0.01% to about 1% by weight ofplatinum and from about 0.1% to about 10% by Weight of combined halogenselected from the group consisting of combined fluorine and combinedchlorine.

3. A process for the production of isobutane from a substantially purenormal butane charge which comprises subjecting said charge at atemperature of from about 400 to about 950 F., and a pressure from about15 to 1500 lbs. per square inch to the action of a catalyst comprising amajor portion of refractory metal oxide, from about 0.01% to about 1% byWeight of platinum and trom about 0.1% to about 10% by weight ofcombined halogen.

4. A process for the production of isobutane from a substantially purenormal butane charge which comprises subjecting said charge at atemperature of from about 400 to about 950 F. and -a pressure of fromabout 15 to 1500 lbs. per square inch to the action of a catalystcomprising of a major proportion of alumina, from about 0.01% to about1% by weight of platinum, and from about 0.1% to about 10% by weight ofcombined halogen selected from the group consisting of combined Ylluorine and combined chlorine.

References Cited in the file of this patent UNITED STATES PATENTS2,324,762 Calhoun et al July 20, 1943 2,381,562 Stewart Aug. 7, 19452,406,869 Upham Sept. 3, 1946 2,479,110 Haensel Aug. 16, 1949 2,602,772Haensel July 8, 1952 2,708,187 Kearby May 10, 1955 OTHER REFERENCESEgloi et al.: Isomerizaton of Bure Hydrocarbons (1942), pages 106, 302and 238.

Sachanen: Chemical Constituents of Petroleum (1945), Page 210.

1. A PROCESS FOR THE PRODUCTION OF ISOBUTANE FROM A SUBSTANTIALLY PURENORMAL BUTANE CHARGE WHICH COMPRISES SUBJECTING SAID CHARGE AT ANISOMERIZING TEMPERATURE UP TO ABOUT 950*F. AND A PRESSURE FROM ABOUT 15TO 1500 LBS. PER SQUARE INCH TO THE ACTION OF A CATALYST COMPRISING AMAJOR PORTION OF REFRACTORY METAL OXIDE, FROM ABOUT 0.01% TO ABOUT 1% BYWEIGHT OF PLATINUM AND FROM ABOUT 0.1% TO ABOUT 10% BY WEIGHT OFCOMBINED HALOGEN.